Auto merge of #44936 - Mark-Simulacrum:rollup, r=Mark-Simulacrum

Rollup of 15 pull requests

- Successful merges: #44124, #44287, #44320, #44694, #44708, #44794, #44797, #44824, #44836, #44840, #44845, #44854, #44889, #44900, #44903
- Failed merges:

13 files changed, 93 insertions, 14 deletions

diff --git a/src/libcore/cmp.rs b/src/libcore/cmp.rs
index 6f86f8caad0..e012cbd76ff 100644
--- a/src/libcore/cmp.rs
+++ b/src/libcore/cmp.rs
@@ -456,7 +456,7 @@ pub trait Ord: Eq + PartialOrd<Self> {
     /// assert_eq!(2, 1.max(2));
     /// assert_eq!(2, 2.max(2));
     /// ```
-    #[stable(feature = "ord_max_min", since = "1.22.0")]
+    #[stable(feature = "ord_max_min", since = "1.21.0")]
     fn max(self, other: Self) -> Self
     where Self: Sized {
         if other >= self { other } else { self }
@@ -472,7 +472,7 @@ pub trait Ord: Eq + PartialOrd<Self> {
     /// assert_eq!(1, 1.min(2));
     /// assert_eq!(2, 2.min(2));
     /// ```
-    #[stable(feature = "ord_max_min", since = "1.22.0")]
+    #[stable(feature = "ord_max_min", since = "1.21.0")]
     fn min(self, other: Self) -> Self
     where Self: Sized {
         if self <= other { self } else { other }
diff --git a/src/libcore/fmt/mod.rs b/src/libcore/fmt/mod.rs
index b84a1deb611..6c251b9eb09 100644
--- a/src/libcore/fmt/mod.rs
+++ b/src/libcore/fmt/mod.rs
@@ -488,13 +488,14 @@ impl<'a> Display for Arguments<'a> {
 /// The origin is: Point { x: 0, y: 0 }
 /// ```
 ///
-/// There are a number of `debug_*` methods on `Formatter` to help you with manual
+/// There are a number of `debug_*` methods on [`Formatter`] to help you with manual
 /// implementations, such as [`debug_struct`][debug_struct].
 ///
 /// `Debug` implementations using either `derive` or the debug builder API
-/// on `Formatter` support pretty printing using the alternate flag: `{:#?}`.
+/// on [`Formatter`] support pretty printing using the alternate flag: `{:#?}`.
 ///
 /// [debug_struct]: ../../std/fmt/struct.Formatter.html#method.debug_struct
+/// [`Formatter`]: ../../std/fmt/struct.Formatter.html
 ///
 /// Pretty printing with `#?`:
 ///
@@ -1321,8 +1322,11 @@ impl<'a> Formatter<'a> {
         self.flags & (1 << FlagV1::SignAwareZeroPad as u32) != 0
     }
 
-    /// Creates a `DebugStruct` builder designed to assist with creation of
-    /// `fmt::Debug` implementations for structs.
+    /// Creates a [`DebugStruct`] builder designed to assist with creation of
+    /// [`fmt::Debug`] implementations for structs.
+    ///
+    /// [`DebugStruct`]: ../../std/fmt/struct.DebugStruct.html
+    /// [`fmt::Debug`]: ../../std/fmt/trait.Debug.html
     ///
     /// # Examples
     ///
diff --git a/src/libcore/internal_macros.rs b/src/libcore/internal_macros.rs
index 9a7914064fd..cb215a38e53 100644
--- a/src/libcore/internal_macros.rs
+++ b/src/libcore/internal_macros.rs
@@ -68,3 +68,22 @@ macro_rules! forward_ref_binop {
         }
     }
 }
+
+// implements "T op= &U", based on "T op= U"
+// where U is expected to be `Copy`able
+macro_rules! forward_ref_op_assign {
+    (impl $imp:ident, $method:ident for $t:ty, $u:ty) => {
+        forward_ref_op_assign!(impl $imp, $method for $t, $u,
+                #[stable(feature = "op_assign_builtins_by_ref", since = "1.22.0")]);
+    };
+    (impl $imp:ident, $method:ident for $t:ty, $u:ty, #[$attr:meta]) => {
+        #[$attr]
+        impl<'a> $imp<&'a $u> for $t {
+            #[inline]
+            fn $method(&mut self, other: &'a $u) {
+                $imp::$method(self, *other);
+            }
+        }
+    }
+}
+
diff --git a/src/libcore/iter/iterator.rs b/src/libcore/iter/iterator.rs
index 36bf9633b4a..e9e31065cf8 100644
--- a/src/libcore/iter/iterator.rs
+++ b/src/libcore/iter/iterator.rs
@@ -518,7 +518,7 @@ pub trait Iterator {
     ///       .for_each(|(i, x)| println!("{}:{}", i, x));
     /// ```
     #[inline]
-    #[stable(feature = "iterator_for_each", since = "1.22.0")]
+    #[stable(feature = "iterator_for_each", since = "1.21.0")]
     fn for_each<F>(self, mut f: F) where
         Self: Sized, F: FnMut(Self::Item),
     {
diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs
index ed39324d488..8d2521b053e 100644
--- a/src/libcore/iter/mod.rs
+++ b/src/libcore/iter/mod.rs
@@ -558,7 +558,7 @@ impl<I> Iterator for Cycle<I> where I: Clone + Iterator {
 #[unstable(feature = "fused", issue = "35602")]
 impl<I> FusedIterator for Cycle<I> where I: Clone + Iterator {}
 
-/// An adapter for stepping iterators by a custom amount.
+/// An iterator for stepping iterators by a custom amount.
 ///
 /// This `struct` is created by the [`step_by`] method on [`Iterator`]. See
 /// its documentation for more.
diff --git a/src/libcore/marker.rs b/src/libcore/marker.rs
index e8fd729b638..f56a9a40332 100644
--- a/src/libcore/marker.rs
+++ b/src/libcore/marker.rs
@@ -122,7 +122,7 @@ pub trait Sized {
 /// [RFC982]: https://github.com/rust-lang/rfcs/blob/master/text/0982-dst-coercion.md
 /// [nomicon-coerce]: ../../nomicon/coercions.html
 #[unstable(feature = "unsize", issue = "27732")]
-#[lang="unsize"]
+#[lang = "unsize"]
 pub trait Unsize<T: ?Sized> {
     // Empty.
 }
diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index 669b93120cf..c869054cee8 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -402,7 +402,7 @@ pub fn align_of_val<T: ?Sized>(val: &T) -> usize {
 /// }
 /// ```
 #[inline]
-#[stable(feature = "needs_drop", since = "1.22.0")]
+#[stable(feature = "needs_drop", since = "1.21.0")]
 pub fn needs_drop<T>() -> bool {
     unsafe { intrinsics::needs_drop::<T>() }
 }
diff --git a/src/libcore/num/wrapping.rs b/src/libcore/num/wrapping.rs
index acdf685e850..ae1b0b3ce11 100644
--- a/src/libcore/num/wrapping.rs
+++ b/src/libcore/num/wrapping.rs
@@ -36,6 +36,7 @@ macro_rules! sh_impl_signed {
                 *self = *self << other;
             }
         }
+        forward_ref_op_assign! { impl ShlAssign, shl_assign for Wrapping<$t>, $f }
 
         #[stable(feature = "rust1", since = "1.0.0")]
         impl Shr<$f> for Wrapping<$t> {
@@ -58,6 +59,7 @@ macro_rules! sh_impl_signed {
                 *self = *self >> other;
             }
         }
+        forward_ref_op_assign! { impl ShrAssign, shr_assign for Wrapping<$t>, $f }
     )
 }
 
@@ -80,6 +82,7 @@ macro_rules! sh_impl_unsigned {
                 *self = *self << other;
             }
         }
+        forward_ref_op_assign! { impl ShlAssign, shl_assign for Wrapping<$t>, $f }
 
         #[stable(feature = "rust1", since = "1.0.0")]
         impl Shr<$f> for Wrapping<$t> {
@@ -98,6 +101,7 @@ macro_rules! sh_impl_unsigned {
                 *self = *self >> other;
             }
         }
+        forward_ref_op_assign! { impl ShrAssign, shr_assign for Wrapping<$t>, $f }
     )
 }
 
@@ -142,6 +146,7 @@ macro_rules! wrapping_impl {
                 *self = *self + other;
             }
         }
+        forward_ref_op_assign! { impl AddAssign, add_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "rust1", since = "1.0.0")]
         impl Sub for Wrapping<$t> {
@@ -162,6 +167,7 @@ macro_rules! wrapping_impl {
                 *self = *self - other;
             }
         }
+        forward_ref_op_assign! { impl SubAssign, sub_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "rust1", since = "1.0.0")]
         impl Mul for Wrapping<$t> {
@@ -182,6 +188,7 @@ macro_rules! wrapping_impl {
                 *self = *self * other;
             }
         }
+        forward_ref_op_assign! { impl MulAssign, mul_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "wrapping_div", since = "1.3.0")]
         impl Div for Wrapping<$t> {
@@ -202,6 +209,7 @@ macro_rules! wrapping_impl {
                 *self = *self / other;
             }
         }
+        forward_ref_op_assign! { impl DivAssign, div_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "wrapping_impls", since = "1.7.0")]
         impl Rem for Wrapping<$t> {
@@ -222,6 +230,7 @@ macro_rules! wrapping_impl {
                 *self = *self % other;
             }
         }
+        forward_ref_op_assign! { impl RemAssign, rem_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "rust1", since = "1.0.0")]
         impl Not for Wrapping<$t> {
@@ -254,6 +263,7 @@ macro_rules! wrapping_impl {
                 *self = *self ^ other;
             }
         }
+        forward_ref_op_assign! { impl BitXorAssign, bitxor_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "rust1", since = "1.0.0")]
         impl BitOr for Wrapping<$t> {
@@ -274,6 +284,7 @@ macro_rules! wrapping_impl {
                 *self = *self | other;
             }
         }
+        forward_ref_op_assign! { impl BitOrAssign, bitor_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "rust1", since = "1.0.0")]
         impl BitAnd for Wrapping<$t> {
@@ -294,6 +305,7 @@ macro_rules! wrapping_impl {
                 *self = *self & other;
             }
         }
+        forward_ref_op_assign! { impl BitAndAssign, bitand_assign for Wrapping<$t>, Wrapping<$t> }
 
         #[stable(feature = "wrapping_neg", since = "1.10.0")]
         impl Neg for Wrapping<$t> {
diff --git a/src/libcore/ops/arith.rs b/src/libcore/ops/arith.rs
index 62007caedd3..8b3d662a6db 100644
--- a/src/libcore/ops/arith.rs
+++ b/src/libcore/ops/arith.rs
@@ -662,6 +662,8 @@ macro_rules! add_assign_impl {
             #[rustc_inherit_overflow_checks]
             fn add_assign(&mut self, other: $t) { *self += other }
         }
+
+        forward_ref_op_assign! { impl AddAssign, add_assign for $t, $t }
     )+)
 }
 
@@ -713,6 +715,8 @@ macro_rules! sub_assign_impl {
             #[rustc_inherit_overflow_checks]
             fn sub_assign(&mut self, other: $t) { *self -= other }
         }
+
+        forward_ref_op_assign! { impl SubAssign, sub_assign for $t, $t }
     )+)
 }
 
@@ -755,6 +759,8 @@ macro_rules! mul_assign_impl {
             #[rustc_inherit_overflow_checks]
             fn mul_assign(&mut self, other: $t) { *self *= other }
         }
+
+        forward_ref_op_assign! { impl MulAssign, mul_assign for $t, $t }
     )+)
 }
 
@@ -796,6 +802,8 @@ macro_rules! div_assign_impl {
             #[inline]
             fn div_assign(&mut self, other: $t) { *self /= other }
         }
+
+        forward_ref_op_assign! { impl DivAssign, div_assign for $t, $t }
     )+)
 }
 
@@ -841,6 +849,8 @@ macro_rules! rem_assign_impl {
             #[inline]
             fn rem_assign(&mut self, other: $t) { *self %= other }
         }
+
+        forward_ref_op_assign! { impl RemAssign, rem_assign for $t, $t }
     )+)
 }
 
diff --git a/src/libcore/ops/bit.rs b/src/libcore/ops/bit.rs
index 0bc5e554cb3..7ac5fc4debf 100644
--- a/src/libcore/ops/bit.rs
+++ b/src/libcore/ops/bit.rs
@@ -593,6 +593,8 @@ macro_rules! bitand_assign_impl {
             #[inline]
             fn bitand_assign(&mut self, other: $t) { *self &= other }
         }
+
+        forward_ref_op_assign! { impl BitAndAssign, bitand_assign for $t, $t }
     )+)
 }
 
@@ -638,6 +640,8 @@ macro_rules! bitor_assign_impl {
             #[inline]
             fn bitor_assign(&mut self, other: $t) { *self |= other }
         }
+
+        forward_ref_op_assign! { impl BitOrAssign, bitor_assign for $t, $t }
     )+)
 }
 
@@ -683,6 +687,8 @@ macro_rules! bitxor_assign_impl {
             #[inline]
             fn bitxor_assign(&mut self, other: $t) { *self ^= other }
         }
+
+        forward_ref_op_assign! { impl BitXorAssign, bitxor_assign for $t, $t }
     )+)
 }
 
@@ -729,6 +735,8 @@ macro_rules! shl_assign_impl {
                 *self <<= other
             }
         }
+
+        forward_ref_op_assign! { impl ShlAssign, shl_assign for $t, $f }
     )
 }
 
@@ -793,6 +801,8 @@ macro_rules! shr_assign_impl {
                 *self >>= other
             }
         }
+
+        forward_ref_op_assign! { impl ShrAssign, shr_assign for $t, $f }
     )
 }
 
diff --git a/src/libcore/ops/unsize.rs b/src/libcore/ops/unsize.rs
index 58da290cfb6..cd896859b16 100644
--- a/src/libcore/ops/unsize.rs
+++ b/src/libcore/ops/unsize.rs
@@ -42,7 +42,7 @@ use marker::Unsize;
 /// [unsize]: ../marker/trait.Unsize.html
 /// [nomicon-coerce]: ../../nomicon/coercions.html
 #[unstable(feature = "coerce_unsized", issue = "27732")]
-#[lang="coerce_unsized"]
+#[lang = "coerce_unsized"]
 pub trait CoerceUnsized<T> {
     // Empty.
 }
diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs
index 4041a3760e5..34d31044653 100644
--- a/src/libcore/ptr.rs
+++ b/src/libcore/ptr.rs
@@ -56,7 +56,7 @@ pub use intrinsics::write_bytes;
 /// This has all the same safety problems as `ptr::read` with respect to
 /// invalid pointers, types, and double drops.
 #[stable(feature = "drop_in_place", since = "1.8.0")]
-#[lang="drop_in_place"]
+#[lang = "drop_in_place"]
 #[allow(unconditional_recursion)]
 pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
     // Code here does not matter - this is replaced by the
diff --git a/src/libcore/sync/atomic.rs b/src/libcore/sync/atomic.rs
index 3dd08e69710..465d31b5f49 100644
--- a/src/libcore/sync/atomic.rs
+++ b/src/libcore/sync/atomic.rs
@@ -926,10 +926,24 @@ macro_rules! atomic_int {
      $stable_cxchg:meta,
      $stable_debug:meta,
      $stable_access:meta,
+     $s_int_type:expr, $int_ref:expr,
      $int_type:ident $atomic_type:ident $atomic_init:ident) => {
         /// An integer type which can be safely shared between threads.
         ///
-        /// This type has the same in-memory representation as the underlying integer type.
+        /// This type has the same in-memory representation as the underlying
+        /// integer type, [`
+        #[doc = $s_int_type]
+        /// `](
+        #[doc = $int_ref]
+        /// ). For more about the differences between atomic types and
+        /// non-atomic types, please see the [module-level documentation].
+        ///
+        /// Please note that examples are shared between atomic variants of
+        /// primitive integer types, so it's normal that they are all
+        /// demonstrating [`AtomicIsize`].
+        ///
+        /// [module-level documentation]: index.html
+        /// [`AtomicIsize`]: struct.AtomicIsize.html
         #[$stable]
         pub struct $atomic_type {
             v: UnsafeCell<$int_type>,
@@ -1339,6 +1353,7 @@ atomic_int! {
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
+    "i8", "../../../std/primitive.i8.html",
     i8 AtomicI8 ATOMIC_I8_INIT
 }
 #[cfg(target_has_atomic = "8")]
@@ -1348,6 +1363,7 @@ atomic_int! {
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
+    "u8", "../../../std/primitive.u8.html",
     u8 AtomicU8 ATOMIC_U8_INIT
 }
 #[cfg(target_has_atomic = "16")]
@@ -1357,6 +1373,7 @@ atomic_int! {
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
+    "i16", "../../../std/primitive.i16.html",
     i16 AtomicI16 ATOMIC_I16_INIT
 }
 #[cfg(target_has_atomic = "16")]
@@ -1366,6 +1383,7 @@ atomic_int! {
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
+    "u16", "../../../std/primitive.u16.html",
     u16 AtomicU16 ATOMIC_U16_INIT
 }
 #[cfg(target_has_atomic = "32")]
@@ -1375,6 +1393,7 @@ atomic_int! {
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
+    "i32", "../../../std/primitive.i32.html",
     i32 AtomicI32 ATOMIC_I32_INIT
 }
 #[cfg(target_has_atomic = "32")]
@@ -1384,6 +1403,7 @@ atomic_int! {
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
+    "u32", "../../../std/primitive.u32.html",
     u32 AtomicU32 ATOMIC_U32_INIT
 }
 #[cfg(target_has_atomic = "64")]
@@ -1393,6 +1413,7 @@ atomic_int! {
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
+    "i64", "../../../std/primitive.i64.html",
     i64 AtomicI64 ATOMIC_I64_INIT
 }
 #[cfg(target_has_atomic = "64")]
@@ -1402,6 +1423,7 @@ atomic_int! {
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
     unstable(feature = "integer_atomics", issue = "32976"),
+    "u64", "../../../std/primitive.u64.html",
     u64 AtomicU64 ATOMIC_U64_INIT
 }
 #[cfg(target_has_atomic = "ptr")]
@@ -1411,6 +1433,7 @@ atomic_int!{
     stable(feature = "extended_compare_and_swap", since = "1.10.0"),
     stable(feature = "atomic_debug", since = "1.3.0"),
     stable(feature = "atomic_access", since = "1.15.0"),
+    "isize", "../../../std/primitive.isize.html",
     isize AtomicIsize ATOMIC_ISIZE_INIT
 }
 #[cfg(target_has_atomic = "ptr")]
@@ -1420,6 +1443,7 @@ atomic_int!{
     stable(feature = "extended_compare_and_swap", since = "1.10.0"),
     stable(feature = "atomic_debug", since = "1.3.0"),
     stable(feature = "atomic_access", since = "1.15.0"),
+    "usize", "../../../std/primitive.usize.html",
     usize AtomicUsize ATOMIC_USIZE_INIT
 }
 
@@ -1752,7 +1776,7 @@ pub fn fence(order: Ordering) {
 /// [`Relaxed`]: enum.Ordering.html#variant.Relaxed
 /// [memory barriers]: https://www.kernel.org/doc/Documentation/memory-barriers.txt
 #[inline]
-#[stable(feature = "compiler_fences", since = "1.22.0")]
+#[stable(feature = "compiler_fences", since = "1.21.0")]
 pub fn compiler_fence(order: Ordering) {
     unsafe {
         match order {